The polyphenylene ether resins are known to be combinable with alkenyl aromatic polymers to provide thermoplastic compositions which are extrudable and moldable into articles of high heat resistance, good impact strength and hydrolytic stability, and good dimensional stability. The compositions can also be formulated into various types, including flame retardant, reinforced, platable, or foamable grades.
The polyphenylene ether resins and methods of their formation are described in the patent literature, including U.S. Pat. Nos. 3,306,874 and 3,306,875 (Hay), and U.S. Pat. Nos. 3,257,357 and 3,257,358 (Stamatoff). A mixture of polyphenylene ether resin with poly(alkenyl aromatics), including polystyrene, rubber modified polystyrene and styrenic co-and terpolymers, is disclosed by Cizek in U.S. Pat. No. 3,383,435.
Compositions of polyphenylene ether resin and styrene resins have been further modified to improve certain properties by the addition of polyesters. Lee, Jr., et al. in U.S. Pat. No. 4,206,154 disclose that the use of a fatty acid-terminated saturated polyester in combination with a polyphenylene ether resin, a styrene resin, a halogenated aromatic flame retardant and ferrocene, results in a composition having enhanced thermal resistance, improved impact strength, and less tendency to undergo dripping when molten. Katchman, et al. in U.S. Pat. No. 4,073,765 disclose that the inclusion of an adipic acid based polyester to an admixture of polyphenylene ether resin, styrene resin and titanate filler, enhances the impact strength and tensile elongation.